View source for CSC231 Powers of 2 in C++

--[[User:Thiebaut|D. Thiebaut]] 13:43, 8 October 2010 (UTC)
----

This exercise is a companion of the same exercise dealing with a [[CSC231 Python program and infinite loops|Python implementation]] of the program.


=Exercise=

* Below is a C++ program, and its complete output

;Question 1
: Do the numbers output by the program look correct?

;Question 2
: Remove the comment sign (//) in front of the last printf.  Compile and run the program again.
: Explain the new output!

;Question 3
: Remove the word ''unsigned'' from the program.  This changes the integer variable from an unsigned variable to a signed one.  
:Change the ''%u'' printing format command by ''%d'' to indicate that you want to print the contents of a signed variable.  
:*Predict the output of the program.  
:*Verify whether you were correct in your prediction!
<br />
==The C++ Program==
<br />

<br />
<source lang="cpp">
// mulby2.cpp
// D. Thiebaut
// To compile and run:
// 
//   g++ -o mulby2 mulby2.cpp
//   ./mulby2
//
#include <stdio.h>

int main() {
  unsigned int x = 1;

    for ( int i=0; i<32; i++ ) {
       printf ( "%u\n", x );
       x = x * 2;
    }

  //printf( "final x = %u\n\n", x );
  return 0;
}

</source>

<br />

==The Output==

<code><pre>

g++  -o  mulby2  mulby2.cpp

./mulby2 

1
2
4
8
16
32
64
128
256
512
1024
2048
4096
8192
16384
32768
65536
131072
262144
524288
1048576
2097152
4194304
8388608
16777216
33554432
67108864
134217728
268435456
536870912
1073741824
2147483648


</pre></code>


<br />

<br />

<br />

<br />

<br />

<br />

<br />

<br />

<br />

<br />

<br />
[[Category:CSC231]][[Category:C++]]